LinPlug Octopus - Manual (Page 59)

As you may have already guessed, the same process can also be applied
to Oscillator 1 to control the overall Amplitude of our sound.
8. Add an envelope to the Envelope Matrix by clicking on the V beside
the Envelope Matrix label. Choose Add Envelope from the menu
and change the type to Amplitude Mult, and then assign it to Osc 1.
Note that 32 envelopes are available in 4 banks of 8 envelopes.
The currently active envelope is highlighted. This time, we'll try to
be a little bit creative about where we place the envelope points. Try
to copy the envelope shape shown below—you don't need to be too
exact, just something roughly similar will do.
Manual 57